• Foundation Design Wayne C Teng Pdf To Excel 2016
• Foundation Design Wayne C Teng Pdf To Excel Converter

I've been looking for a reference as to how to determine the max soil pressure for a footing that has moments in both directions, but only has partial bearing. The moment in one direction would the load in the kern (if it were the only moment), and the moment in the other direction would put the load outside the kern. I can't find a reference on this in my foundations book, and I could go through the math of it (but that would take a REALLY long time, and I honestly don't want to spend an entire day to figure it out), but I figured someone else has to have done this before.My first inclination was to take the max pressure of the moment causing partial bearing and adding that to the max pressure caused by the full bearing (M/S), then I realized that I couldn't us the full S of the footing (for the smaller moment) because the whole footing isn't in bearing anymore. I tried estimating the amount of the footing that would be in bearing and using that S. That would get me close, but I'm really trying to be exact because I'm evaluating a program. The line of zero bearing stress is not perpendicular to either edge of the footing because of the moments in both directions, but again, I don't know how to address this without a day-long geometry session.

RE: footing with biaxial moment (Structural) 28 Jan 09 09:37. As a first approximation, calculate the resultant moment acting on the footing, i.e. The vector sum of the two moments.

Assume the line of zero pressure occurs parallel to the resultant moment (using the right hand rule). Take an educated guess where the zero pressure line is and determine whether the resulting stress block satisfies both load and moment. Modify the position of the zero pressure line until load and moment are approximately satisfied.Then check the moment normal to the resultant vector.

If it is not zero, modify the direction of the zero pressure line until it is close enough.Best regards,BA RE: footing with biaxial moment (Structural) 28 Jan 09 17:17. From personal experience, here are my views:1. As suggested by MSQUARED48, avoid the situation to the best you can.2. As JLNJ pointed out, use FEM with compression only spring.3. For personal satisfaction, you can write your own spreadsheet program assuming the footing and soil both are linear elastic (linear stresses). The difficult part is once a corner has developed negative pressure (uplift), the bearing area is reduced, and the new bearing area/neutral axes need to be found, its properties re-calculated (quite mathematically challenging), and load redistributed.

The iteration process stops when the footing is fully in bearing.Have fun. RE: footing with biaxial moment (Structural).

There still seems to be something wrong with the results you guys are getting. First of all, a 10'x10'x2' footing weighs approximately 30 kips. I don't know what you mean by 'an appropriate DL factor' but, for the sake of the problem, let us say that:P = 20kMx = 88k-ftAssume that My = 0 for now.The eccentricity in the x direction is 88/20 = 4.4', so for a 10'x10' footing, the effective length of bearing on the soil is (5 - 4.4)3 = 1.8' and the effective width is 10'.The soil pressure has a triangular distribution. Average pressure = 20/(10.1.8) = 1.11 ksf.

Maximum pressure is 2.22 ksf. Minimum pressure is zero. So far, we have said that My = 0.If My = 4k-ft, surely the maximum pressure will increase slightly, so the maximum pressure by my calculation is approximately 2.22 + 0.13 = 2.35 ksf.Am I misinterpreting the problem?Best regards,BA RE: footing with biaxial moment (Structural). Chicuck,No, there is no uplift on the footing. The axial load from the column (for the controlling load combination of 0.6DL-W is 2.818k. While the weight of the footing is 30k, you can only use 18k (because the load combination is 0.6DL-W), hence the TOTAL P=18k+2.818=20.818K (as noted in an earlier post). I am not considering any soil overburden on the footing (whether that is right or wrong is irrelevant to what I am trying to do), I can specifiy overburden in the program, but all I want to do is verify that any situation that the program is faced with will be done correctly.BA,No, the max pressure is around 1.9ksf (for P=20.818, Mx=87.842k-ft, and My=4.226k-ft).RE: footing with biaxial moment (Structural) 30 Jan 09 10:25.

Foundation Design Wayne C Teng Pdf To Excel 2016

The AASHTO Code has a method for coming up with the qmax as well. See Figure 4.4.7.1.1.1C in the 17th Edition.I am not sure if the same figure appears in the new one (LRFD only). I think it is strange that the code includes this figure because elsewhere in the code they do not permit bridge foundations to be loaded outside the kern.On another note, we design sign and billboard foundations often enough, and it is entirely uneconomical to design a spread foundation with the resultant within the kern for wind load.

It would irresponsible of an engineer to require the load to remain within the kern in such a circumstance. RE: footing with biaxial moment (Structural) 10 Feb 09 12:16. StructuralEIT-The 'S' used in the bearing pressure calculations, has no name, it's simply a variable defined by the formula.You're right, e y is 0. To avoid dividing by zero, I've adjusted e y (and e x) by ε, as shown in the formulas on sheet 1. Ε is defined as.001 feet, but that definition is not shown anywhere on the printout.px is the soil pressure at the center of the footing, if M x=0k'. I use px to calculate the bending moment at the center of the footing, where I believe it is maximum.Again, I don't know where the soil pressure formulation comes from.

I got it at least 20 years ago and have verified it against many other sources over those 20 years. It is always dead on. RE: footing with biaxial moment (Structural). Miecz- Thanks.miecz and willis-Would it be possible for both of you to plug in the following loads in your respective sheets and tell me what you get?footing is 9'x9'x2' (but the self weight of the footing is already figured into P - using the 0.6DL factor)P=18.632KMx=71.52k-ftMy=5.646k-ftUsing miecz's formulas I'm coming up with 2306psf (which is roughly what I would expect), but this program I'm checking is showing 3380psf (almost 50% higher). I found another method that I was trying out, but that's only giving me 1330psf (which is way too low, so I'm throwing that out). RE: footing with biaxial moment (Structural) 10 Feb 09 14:15. With only P and Mx, the eccentricity is 3.84', or 0.66' from the edge of the footing.

With a triangular distribution of pressure, the effective width of the footing is 3. 0.66 = 1.98' and the maximum pressure = 2.09 ksf.Now, considering My = 5.64k' and a section modulus of S of 1.98.9^2/6 = 26.7 for the effective portion of the footing, the additional stress is M/S = 0.21 ksf.Adding the two together gives 2.30 ksf.Best regards,BA RE: footing with biaxial moment (Civil/Environmental) 10 Feb 09 14:24. The AASHTO Standard Specs have Figure 4.4.7.1.1.1C to solve this kind of problem.

It comes from the old AREA Railway Manual. It gives the same results, but, because it is a graphical solution, it gives information that formulas do not. Specifically, with the loads and dimensions you have, the bearing pressure is very sensitive to small changes in vertical load or eccentricity.

Just reducing P 6% to 17.56 kips raises the bearing pressure to 3380 psf. Could your program be fiddling with your input?

Foundation Design Wayne C Teng Pdf To Excel Converter

RE: footing with biaxial moment (Structural) 12 Feb 09 17:47. Here is one way to do it.On the attached sketch, Vol. Abcd is the volume under the stress block.Cx and Cy are measured from the edge of footing to the centroid of the stress block.h is the height at point a.kh is height at point c.0 is the height at b, c and e.Using Excel, one can experiment with different x and k values until Cx = A/2 - P/Mx and Cy = A/2 - P/My.Finally, calculate 'h' to satisfy the equation that the volume under the stress block is equal to P, the applied load.Best regards,BA.RE: footing with biaxial moment (Structural) 14 Feb 09 18:52.

If anyone is interested, the RISAFoot program (even the free Demo version) provides information that can be used to verify a bi-axial soil bearing profile.That program will show you the soil bearing pressure at each of the 4 corners and will also display the distace from the point of maximum compression to the neutral axis location.If you know that information it is not all that difficult to verify that the total pressure load equals the applied vertical load. I did this for one of our users yesterday. It takes me awhile to remember how to do the integration, but once I remember then it's not that bad.You can even use this same information to verify that the centroid of the soil pressure corresponds to the load eccentricity location.

But, the integration gets more complicated, and I tend to 'guesstimate' it for my hand calculations instead. RE: footing with biaxial moment (Structural) 18 Feb 09 18:45. In the attached diagram, the pressure at corner b and d is zero. The pressure at c is k times the pressure at a, namely h. The volume abcd is actually a truncated triangular pyramid, so can be expressed as abe - cde. Call the midwife christmas special rapidshare movies. The volume and centroid of a regular pyramid is well known, so no need to integrate.The procedure is to guess at x and k and iterate to a correct solution such that Cx and Cy correspond to the known location of the load P.

When this has been found, the highest pressure, h (at point a) can be found by equating the volume of abcd to applied load P.A bit messy, but it can be done.Best regards,BA.RE: footing with biaxial moment (Structural) 19 Feb 09 06:39.